Modular and adjustable return air plenum for hvac systems

ABSTRACT

A modular return air plenum for HVAC systems is provided that can be used to support a base an air handler unit or furnace in an HVAC system. The modular return air plenum is customizable in its width due to the use of one or more corner pieces, that when coupled together, form a connected return air plenum that is modular and adjustable in size. The modular return air plenum may include additional modular pieces that are integrated between the corner pieces. More than one modular return air plenum can be formed together and then stacked onto each other in order to increase a height of the combined modular return air plenum and provide for a taller modular return air plenum to best suit the support base needed for an air handler unit or furnace in the HVAC system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application which claims priority to U.S. Provisional Patent Application No. 63/184,362 filed on May 5, 2021, which is incorporated in its entirety.

FIELD OF THE DISCLOSURE

The present invention relates to a new system for a modular and adjustable return air plenum for supporting as a base an air handler unit or furnace as part of an HVAC system in a facility.

BACKGROUND

Return air plenums are an important part of any Heating, Ventilation, and Air Conditioning (HVAC) system, whether in a commercial or residential facility. A plenum is essentially a box that is part of and connects a return trunk duct. The plenum has a critical function to bring in and circulate air. Each HVAC system typically uses at least two plenum boxes which are a supply plenum box and a return plenum box. A return plenum box is also referred to as a return air plenum. A supply plenum works by taking in the new cool or warm air from the heater or air conditioning system and, in turn, distributing the cool air throughout the building using the HVAC's ductwork. A return plenum takes in that used air and, using the ductwork, sends the used air back to the core HVAC system, which is then recycled as conditioned air later.

Additionally, the return air plenum is a box that supports a furnace or an air handler unit. There are many different types of air handler units and furnaces utilized by HVAC systems. LENNOX, TRANE, GOODMAN, CARRIER, and all other manufacturers of HVAC units produce HVAC products, including air handler units and furnaces. Existing return air plenums are typically large, rectangular, metallic boxes. Each manufacturer, such as LENNOX, TRANE, GOODMAN, CARRIER, and other manufacturers produces their own air handlers and return air plenums in varying sizes. A major problem, if any changes are made later on to the air handler unit and HVAC system during service and repair or installation, is finding the correct sized return air plenum to fit the air handler unit or furnace. It is very difficult to obtain from the manufacturer a correct size return air plenum when changes are made to the air handler unit or furnace. Because return air plenums are currently manufactured as large, uniform metal boxes that are not adjustable, they take up a great deal of storage space, which means that manufacturers and retail stores do not want to carry the return air plenums in large quantities or have a large inventory of return air plenums due to the problems in storing and displaying such large return air plenum boxes.

Currently, when an HVAC technician or contractor has to make repairs or changes to an air handler unit or furnace and has to locate a new return air plenum to fit under the air handler unit or furnace, the HVAC technician is often forced to find any kind of return air plenum that is estimated to have the closest size to what is needed. Next, the HVAC technician must then try to make piecemeal repairs to alter the dimensions and shape of the return air plenum to best fit the air handler unit currently being repaired or installed. This is not ideal as it would have been better to have the corresponding return air plenum for the corresponding air handler unit having the correct size and fit.

Accordingly, there is a need for an alternative to the existing overly large, bulky, uniform return air plenums that currently exist on the market that overcomes these existing deficiencies.

SUMMARY

The present description includes one or more embodiments for a system for a modular return air plenum for HVAC systems, comprising a formed base connected to an underside of a formed cap. In a non-limiting embodiment, the base comprises one or more base corner pieces, whereby the one or more base corner pieces are L-shaped and include a first base corner piece that is generally perpendicularly oriented to a second base corner piece. Further, the base may include one or more base modular pieces wherein the one or more base modular pieces are configured to connect to another base corner piece or to a base modular piece, wherein each base corner piece and each base modular piece each have a first mating end and a second mating end. Additionally, the first mating end of each base corner piece is configured to mate with the second mating end of another base corner piece or with the second mating end of another base modular piece, wherein when the one or more base corner pieces are connected in a rectangular or square like arrangement with each other and/or with any base modular pieces, the base of the modular return air plenum is formed. Accordingly, a base of a modular return air plenum may include only base corner pieces and does not include any base modular pieces if the final size (e.g., area) of the formed modular return air plenum fits the area of the HVAC unit that the modular return air plenum is supporting.

The cap is symmetrical with the base and includes one or more cap corner pieces, wherein the one or more cap corner pieces are L-shaped, and include a first cap piece that is generally perpendicularly oriented to a second cap piece, and includes one or more cap modular pieces wherein the one or more cap modular pieces are configured to connect to another cap corner piece or to another cap modular piece, wherein each cap corner piece and each cap modular piece each have a first mating end and a second mating end. The first mating end of each cap corner piece is configured to mate with the second mating end of another cap corner piece or with the second mating end of another cap modular piece, wherein when the one or more cap corner pieces are connected in a rectangular or square like arrangement with each other and/or with any cap modular pieces, the cap of the modular return air plenum is formed, wherein the formed cap of the modular return air plenum comprises a cap interior cavity/

The modular return air plenum comprises the formed cap removably attached to the top surface of the formed base, wherein a width and a length of the modular return air plenum is customizable to suit and support an HVAC unit. Further, in another non-limiting embodiment, each assembled modular return air plenum is stackable onto another assembled modular return air plenum when additional height is required to suit and support the HVAC unit. The modular return air plenum is configured to support an air handler unit or a furnace in an HVAC system. In one or more non-limiting embodiments, each top surface of each base corner piece comprises a boss or a protruding piece that is configured to fit within a hollow underside of the cap. Further, each base corner piece comprises a longer side that is perpendicular to a shorter side. wherein an end piece of the longer side comprises a protruding bar like member, wherein the end piece of the longer side is the first mating end. Additionally, an end piece of the shorter side comprises a slot configured to receive the protruding bar like member in order to mate with either a base modular piece of the one or more base modular pieces or to mate with another base corner piece, wherein the end piece of the shorter side is the second mating end. In a non-limiting embodiment, the second mating end is configured to tightly mate with the first second mating end by press fit or friction fit.

In one or more non-limiting embodiment, the modular return air plenum comprises a base without a cap having one or more base corner pieces and/or one or more base modular pieces that can extend the length and width of the formed modular return air plenum if needed.

Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure are described in detail below with reference to the following drawings. These and other features, aspects, and advantages of the present disclosure will become better understood with regard to the following description, appended claims, and accompanying drawings. The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations and are not intended to limit the scope of the present disclosure.

FIG. 1 depicts a pictorial illustration of a prior art existing air handler unit and return box.

FIG. 2 depicts a pictorial illustration of a prior art return and supply air flow for HVAC systems.

FIG. 3 depicts a pictorial illustration of a perspective view of a modular return air plenum.

FIG. 4 depicts a pictorial illustration of a bottom perspective view of the modular return air plenum shown in FIG. 3.

FIG. 5 depicts a pictorial illustration of a bottom view of the modular return air plenum shown in FIG. 3.

FIG. 6 depicts a pictorial illustration of a cross-sectional view taken along section line A-A shown in FIG. 3 of two modular return air plenums stacked on top of each other for achieving additional height.

FIG. 7 depicts a pictorial illustration of another embodiment of a modular return air plenum and a modular cap with an HVAC unit positioned above the modular cap and modular return air plenum.

FIG. 8 depicts another pictorial illustration of the modular return air plenum and modular cap shown in FIG. 7.

FIG. 9 depicts a pictorial illustration of a partial view of a corner piece connected to a modular piece for the modular return air plenum shown in FIG. 7.

FIG. 10 depicts a partial top view of the cap positioned over the corner piece and modular piece shown in FIG. 9.

FIG. 11 depicts a view of corner pieces shown in FIG. 7 connected to each other to form a base of a return air plenum.

FIG. 12 is a flowchart of an exemplary method of assembling a return air plenum using one or more corner pieces and modular pieces of a cap and a base of the return air plenum.

DETAILED DESCRIPTION

The present description is drawn to a modular and adjustable return air plenum that can be utilized with HVAC systems to support or place under an air handler unit or a furnace. In one or more non-limiting embodiments, the modular and adjustable return air plenum may be adjustable in length and width and may also be stackable to create the proper height required to suit the air handler unit, furnace, or other unit that the return air plenum is supporting. Additional details are provided with respect to the Figures.

FIG. 1 shows a pictorial illustration of a prior art air handler unit and return air plenum. Air handler unit 102 and return air plenum 104, as shown in FIG. 1, are utilized by HVAC systems to provide proper air flow and supply in a facility. Typically, in use, the air handler unit 102 sits on top of the return air plenum 104, as shown in FIG. 1. HVAC unit manufacturers may provide a solid, metallic, rectangular return air plenum 104 and the contractor or HVAC technician must cut an additional hole in the top or side of the return box 104 for any ductwork and air to flow through the return air plenum 104.

FIG. 2 shows an example of a prior art HVAC system and the relationship for the supply air and return air as incorporated in the supply plenum and return air plenum. FIG. 2 shows an example of a supply plenum 206 positioned over another box unit holding an evaporator coil 208. The furnace 202 is positioned beneath the supply plenum 206 and evaporator coil 208 as shown in FIG. 2. The prior art return air plenum 104 is positioned beneath the furnace 202. The cold air return drop unit 204 is connected to the side of the return air plenum 104 as shown in FIG. 2.

There should be a temperature drop across the evaporator coil 208 such that the temperature of the return air directed to the supply plenum 206 is lower that the temperature of the air in the return air plenum 104. It is noted that the arrangement shown in FIG. 2 of components is just an example as there are many ways that an HVAC system may be organized and installed in order to best suit the heating and cooling and ventilation needs of a particular facility.

Normally, a return air plenum 104 is connected to the cold air return drop unit 204 whereby an HVAC technician cuts a hole in the return air plenum 104 and connects that return air plenum to the cold air return drop unit 204 with one or more pipes or ducts. The air contained in the return air plenum 104 can then be directed up through the cold air return drop 204 in order to be recycled in the HVAC system.

As noted above, it is very difficult for a contractor or HVAC technician to locate a proper sized return air plenum 104 if the air handler unit 102 or furnace 202, as shown in the exemplary prior art FIGS. 1-2, is not purchased with the correct return air plenum 104. The HVAC technician usually has to locate the next best fitting and available return air plenum 104 and adjust the dimensions of the return air plenum 104 using any tools or pieces the contractor has to secure the return air plenum 104 in place and achieve a proper fit. This current situation is not ideal and may lead to malfunctions in the proper functioning of the air handler unit 102 or furnace 202 positioned over the best fitting and available return air plenum 104. It is noted that the term “HVAC unit” as used herein may be used to refer to an air handler unit 102 or a furnace 202 or any other HVAC unit in one or more non-limiting embodiments.

FIG. 3 shows a modular and adjustable return air plenum 300 according to a non-limiting embodiment. The return box air plenum 300 shown in FIG. 3 is an example of a single level return air plenum 300. FIG. 6 shows a taller return air plenum 600 made up of two return air plenums 300 stacked on top of each other with the same components of return air plenum 300 as shown in FIGS. 3-5 and as described further below. A unique advantage of the modularity and adjustability of the return air plenums 300 (and return air plenums 700 shown in FIGS. 7-11) is that the height and width and length are all configured to be adjustable via the modular pieces of the return air plenum 300.

As noted above, return air plenum 300 as shown in FIGS. 3-5 is shown as being one level. It is noted that the term “return air plenum” may interchangeably be referred to as a “return box” in one or more non-limiting embodiments.

In a non-limiting embodiment, return air plenum 300 has four main sides including a front side 334, back side 336, left side 338, and right side 340. As shown in FIG. 3, the front side 334 and back side 336 are opposite or parallel to each other and the left side 338 and right side 340 are opposite or parallel to each other. Each side 334, 336, 338, and 340 together forms a rectangular or square shaped box or the assembled return air plenum 300.

In one or more non-limiting embodiments, return air plenum 300 includes at least four corner pieces 302 a, 302 b, 302 c, and 302 d as shown in FIG. 3-5. Further, the return air plenum 300 includes at least four modular pieces 304 a, 304 b, 304 c, and 304 d as shown in FIG. 3-5.

Advantageously, the return air plenum 300 and return air plenum 700 shown in FIGS. 7-11 is designed to be modular and adjustable in its size. Accordingly, as many modular pieces 304 a-d can be added to any side, including the front side 334, back side 336, left side 338, and right side 340 of the return air plenum 300 as needed to achieve the proper height 312, width 314, and depth 316, as shown in FIG. 3, of the return air plenum 300 to best suit the unit (e.g., air handler unit 102 or furnace 202 shown in FIGS. 1-2) that the modular return air plenum 300 is intended to support. Accordingly, the modular pieces 304 a-d, in one or more non-limiting embodiments, can be added in any number or arrangement in between the corner pieces 304 a-d in the embodiment shown in FIG. 3-FIG. 5 in order to achieve the correct height 312, width 314, and length 316 for the return air plenum 300 and the correct overall height, width, and length for each side 334-340 of the return air plenum 300. Further, as noted above, the return air plenum 300 can be stacked on top of each other, as shown in FIG. 6, in order to have more than one level or layer in order to provide the correct and desired height 312 for the overall return air plenum 300 or 600.

In cases where the HVAC technician needs a taller return air plenum 300 to support a specific type of unit, the HVAC technician can stack any number of return air plenums 300 arranged as desired and also having the desired width 314 and length 316 on top of each other.

In a non-limiting embodiment, each side 334-340 of the return air plenum 300 may be composed of at least two corner pieces 302 a-d and at least one modular piece 304 a-d located between the two corner pieces 302 a-d. If the HVAC specialist wants to increase the width or length of any particular side 334-340 of the return air plenum 300, the HVAC specialist may add more modular pieces 304 a-d in between the corner pieces 302 a-d. While one modular piece 304 a, for example, is shown located between corner piece 302 a and 302 b on the front side 334 of return air plenum in FIG. 3, the HVAC technician is free to add more modular pieces 304 a to create more width or length to each side 334-340.

In a non-limiting embodiment, each modular piece 304 a-d has at least two top connection joints 332, as shown in FIG. 3 on the front side 334 of the return air plenum 300. The top connection joints 332 enable each modular piece 304 a-d to connect on either side of the modular piece 304 a-d to another modular piece 304 a-d in order to increase the width or overall size of a particular side 334-340 of the return air plenum 300. Further, the at least two top connection joints 332 of each modular piece 304 a-302 d enable the modular piece 304 a-304 d to connect on either side of the modular piece 304 a-304 d to a connection joint, such as connection joint 342 or 344 of each corner piece 302 a-302 d.

In a non-limiting embodiment, each corner piece 302 a-302 d is designed to have an L-shape. The L-shaped corner pieces 302 a-302 d include a first piece 326 that is perpendicular to a second piece 328 of the L-shaped corner pieces 302 a-302 d, as shown in FIG. 3 and in FIG. 5. The first piece 326 and the second piece 328 of the corner pieces 302 a-302 d are perpendicularly joined at a joint 324 as shown in FIG. 3 and also in FIG. 5 as well. Each corner piece 302 a-302 d will make up the corners of the return air plenum 300 and will form a part of either side 334-340 of the return air plenum 300, while the modular pieces 304 a-304 d form the center or middle portion of each respective side 334-340 of the return air plenum 300 in a non-limiting embodiment. The corner pieces 302 a-302 d and modular pieces 304 a-304 d are designed to fit together via contact and friction and are held together in such a manner, in one or more non-limiting embodiments. In other embodiments, additional fasteners or adhesives may be used or any other means of attachment to ensure that the corner pieces 302 a-302 d and modular pieces 304 a-304 d are firmly connected or attached together.

Ultimately, the return air plenum 300 will be generally rectangular or square shaped depending on the size of each corner piece 302 a-302 d and each modular piece 304 a-304 d and depending on how many modular pieces 304 a-304 d are added by the HVAC technician to best accommodate or support an attached air handler unit 102 or furnace 202. As noted above, the return air plenum 300 can be oriented in any direction as needed to support the unit (e.g., air handle unit 102 or furnace 202) that the return air plenum 300 is attached to or otherwise coupled to or supporting. The assembled return air plenum 300 may be positioned vertically, horizontally, or any other orientation or direction.

Each corner piece 302 a-302 d and each modular piece 304 a-304 d may have one or more protrusions or top pieces 308, as shown in FIG. 3, protruding from a top surface of the corner piece 302 a-302 d and modular piece 304 a-304 d. The protrusion 308 may have a gap or space 310 between each protrusion 308 on each corner piece 302 a-302 d in one or more non-limiting embodiment. The protrusion 308 extends from a top surface 320 of the return air plenum 300. As further described later below with respect to FIGS. 4-5, the protrusions 308 may be part of a square shaped column 402 that extends through the body of the corner pieces 302 a-302 d and column 416 of the modular pieces 304 a-304 d, as shown in FIGS. 4-6. In a non-limiting embodiment, the protrusions 308 are square shaped as shown in FIG. 3, but in other alternative embodiments, the protrusions 308 may be circular shaped, oval shaped, rectangular shaped, triangular shaped, or any other shape desired.

Once the corner pieces 302 a-302 d and the modular pieces 304 a-304 d are assembled in the desired arrangement and having the desired width and length, the return air plenum 300 or at least one level or layer of a return air plenum 300 is formed. Further, there will be a rectangular hole or cavity 306 in the center of the return air plenum 300 as shown in FIGS. 3-5. The hole or internal cavity 306 will be defined by each side 334-340 of the return air plenum 300.

As shown in FIG. 3-5, each corner piece 302 a-302 d can join with another modular piece 304 a-304 d or another corner piece 302 a-302 d. Each corner piece 302 a-d has at least two connection joints 342 and 344 that can join with another modular piece 304 a-304 d or with another corner piece 302 a-302 d if the HVAC technician does not want to add any modular pieces 304 a-d between all the corner pieces 302 a-302 d in order to have a smaller return air plenum 300. In such a case, all the corner pieces 302 a-302 d would connect together to form a square shaped return air plenum 300, which may be suitable in some instances to support certain units in some HVAC systems and some applications. The corner pieces 302 a-302 d and modular pieces 304 a-304 d are intended to fit together on either side of each corner piece 302 a-302 d and modular pieces 304 a-d much like puzzle or jigsaw pieces.

Turning to FIGS. 4-5, FIG. 4 shows a bottom perspective view of return air plenum 300 and FIG. 5 shows a bottom view of return air plenum 300 according to one or more non-limiting embodiments. The bottom views shown in FIGS. 4-5 illustrate that, in one or more non-limiting embodiments, the corner pieces 302 a-302 d have at least five square columns 402 that extend through the body of the corner shaped piece 302 a-302 d from the top surface 320 to the bottom surface 322 of each corner shaped piece 302 a-302 d. One of ordinary skill in the art understands that more or less columns 402 may be used for each corner piece 302 a-302 d in alternative embodiments. Each column 402 may have a bore 404 extending from top to bottom of the column 402. As noted above, the protrusions 308 shown in FIG. 3 are part of the square columns 402 that extend from the top surface 320 to the bottom surface 322 of each corner piece 302 a-d. As shown in FIGS. 4-5, each column 402 may be surrounded by one or more channels 440 or cavities in the underside of the body of the corner pieces 302 a-302 d and separated by partitions 442 from each other.

Similarly, as shown in FIGS. 4-5, each modular piece 304 a-304 d may have its own column 416 extending through the body of the modular piece 304 a-304 d from a top surface 320 to a bottom surface 322. Each column 416 of each modular piece 304 a-304 d may have its own internal bore 419 as shown in FIGS. 4-5. Further, the column 416 may be surrounded by channels 418 or cavities in the underside of the body of the modular piece 304 a-304 d and that are separated by partitions 420 from each other.

It is intended that the return air plenum may be lightweight, which is a function and feature of the hollow columns 402 of each corner piece 302 a-302 d and the hollow columns 416 of the modular pieces 304 a-304 d. Further, in a preferred embodiment, the corner pieces 302 a-302 d and the modular pieces 304 a-304 d may be made from or largely incorporate a plastic material, although any other desired material may alternatively or additionally be used during manufacturing. Plastic may be more lightweight and flexible than metal, which is why it may be preferable to manufacture the return air plenum 300 from a plastic material. It is noted that the HVAC technician is able to drill any holes needed into the return air plenum 300 in order to connect to another unit or element in the HVAC system (e.g., such as the cold air return drop unit 208 shown in FIG. 2) or to pass ductwork through.

In a non-limiting embodiment, the height 350 as shown in FIG. 4 of each corner piece 302 a-302 d and the height 412 of each modular piece 304 a-304 d may be the same so that neither the corner piece 302 a-302 d nor the modular pieces 304 a-304 d used in the return air plenum 300 are taller or shorter than the other. Each modular piece 304 a-304 d is level with an adjacent corner piece 302 a-302 d. In a non-limiting embodiment, the height 350, as shown in FIG. 4, of each corner piece 302 a-302 d and the height 412 of each modular piece 304 a-304 d may be 6 inches high or tall. The width 410 of each modular piece 304 a-304 d may be at least 2 inches wide in a non-limiting embodiment. One of ordinary skill in the art will understand that these numbers are exemplary and non-limiting.

FIG. 6 is a cross-sectional view of each return air plenum 300 taken along line A-A shown in FIG. 3. FIG. 6 has two return air plenums 300 that are composed of corner pieces 302 a-302 d and modular pieces 304 a-304 d, whereby the two return air plenums 300 are stacked on top of each other. The height 602 of the combined return air plenums 300 that form return air plenum 600 may be the equivalent of the addition of the individual heights 312, as shown in FIG. 3, of each return air plenum 300. In a non-limiting embodiment, if the height 312 of each return air plenum 300 is 6 inches high, then the overall height 602 of two return air plenums 300 may be 12 inches high. As noted above, the HVAC technician may stack as many assembled return air plenums 300 as needed on top of each other in order to achieve the desired height to accommodate a particular unit in the HVAC system in which the return air plenum 300 is being utilized.

As shown in the cross-sectional view in FIG. 6, the protrusions 308 on each corner piece 302 a-302 d and modular piece 304 a-304 d are hollow and extend into the columns 402 and 416 of each corner piece 302 a-302 d and modular piece 304 a-304 d in a non-limiting embodiment. Further, all the corner pieces 302 a-302 d and modular pieces 304 a-304 d connect to each other along connection joints that are designed to fit with the other.

Notably, different manufacturers make different sized air handler units 102 and furnaces 202 that require return air plenums 300. For example, one manufacturer may produce an HVAC unit, such as an air handler 102 or furnace 202, that is short but very wide whereas another manufacturer may produce an HVAC unit that is skinny and tall which requires different sized return air plenums 300. A great advantage of the return air plenums 300 as described herein and shown in FIGS. 3-6 is that by adding or taking away more modular pieces 304 a-304 d, the HVAC technician may make each return air plenum 300 wider or narrower or smaller. Accordingly, the return air plenums 300 shown in FIGS. 3-6 are better than existing return air plenums 102, as shown in FIG. 1-2, which come in one size and are not adjustable in size, and are also bulky, not lightweight, and are hard to store because these conventional return air plenums 104 are usually so large. Advantageously, manufacturers and stores will be able to store much more of the return air plenums 300, as shown in FIGS. 3-5, because they are lightweight and modular in design, so any of the integral components and pieces (e.g., 302 a-302 d and 304 a-304 d) could be separately stacked and stored unassembled or assembled in smaller structures than the conventional return air plenums 104.

It is noted that the return air plenum 300 shown in FIGS. 3-6 are one example of a modular and adjustable return air plenum 300. Many other modifications in keeping with the spirit of this present disclosure may be made in alternative configurations.

FIGS. 7-11 show another example of a modular return air plenum 700 in one or more non-limiting embodiment that includes similar aspects with the modular return air plenum 300 shown in FIGS. 3-6, and further includes some differences. As shown in the system of FIGS. 7-11, the modular return air plenum 700 may be made up of a flat cap 702 that can be assembled having an assembly of cap corner pieces 708 a-708 d that either connect to each other or that include one or more modular piece 710 a-710 d positioned between each cap corner pieces 708 a-708 d when the cap 702 needs to be expanded in size to accommodate a larger HVAC unit that will be supported by the connected cap 702 and base 704. Once the cap 702 is assembled, the assembled cap 702 is positioned by pushing onto the top surfaces of a formed base 704 in order to form a single modular return air plenum 700. As shown in the system of FIG. 7, an air handler 104 or any other HVAC unit may be positioned on top of a flat cap 702 which is positioned over a base 704. The cap 702 may act as a cover and stabilizer to stabilize the connection between the base 704 of the return air plenum 700 and the air handler unit 104. In a non-limiting embodiment, the flat cap 702 is a separate piece from the return air plenum 704 and is assembled to fit over the return air plenum 704. Further, the flat cap 702 is an assembly of cap corner pieces 708 a, 708 b, 708 c, and 708 d and any cap modular pieces 710 a, 710 b, 710 c, and 710 d used to enlarge or widen each side of the flat cap 702 to properly fit the area of the HVAC unit (e.g., an air handler unit 104 as shown in FIG. 7 or a furnace 202 as shown in FIG. 2). In other non-limiting embodiments, the flat cap 702 is part of the modular return air plenum 704 and is not a separate, removable piece in one or more non-limiting embodiments.

The base 704 of the return air plenum 700, as shown in FIGS. 7-11, may have base corner pieces 720 a-720 d and base modular pieces 722 a-722 d having the same essential elements as described above with some differences as shown in FIGS. 7-11. For example, the base corner pieces 720 a-720 d may be designed to be asymmetrical with a shorter side 705 and a longer side 707 as shown in FIG. 7 and FIG. 8. The shorter side 705 and the longer side 707 may still be joined perpendicularly (for example, at joint 709 as shown in FIG. 7) and make up each base corner piece 720 a-720 d. This asymmetrical configuration for the base corner pieces 720 a-720 d, whereby having one side 705 being shorter, and one side being longer 707 may make it easier to manufacture in some non-limiting embodiments. The interiorly placed base modular pieces 722 a-722 d for the base 704 of the return air plenum 700 may still be connected between each corner piece 720 a-720 d. Further, the HVAC technician or other user may still add as many or take away as many base modular pieces 722 a-722 d as needed to achieve the proper height, width, and length on the modular return air plenum 700 to fit and support an area of an HVAC unit.

FIG. 8 shows the cap 702 positioned over the base 704 of the return air plenum 700. The line 802 shown in FIG. 8 shows where the flat cap 702 joins with the base 704 when the cap 702 is pressed onto the top surface of the assembled base 704.

As shown in FIG. 8, the cap 702 and the base 704 of the return air plenum 700, when fully assembled, can form a rectangular or square shape having an interior cavity 706. As shown in FIG. 8, once the base corner pieces 720 a-720 d and the base modular pieces 722 a-722 d are assembled, an interior cavity 706 is formed that is defined by all of these pieces of the cap 702 as positioned onto the base 704 of the return air plenum 700.

Similar to the base 704 of the return air plenum 700, the cap 702 is an assembly of cap corner pieces 708 a-708 d and cap modular pieces 710 a-710 d such that the HVAC technician or other user can connect each cap corner piece 708 a, 708 b, 708 c, 708 d to each other directly. Further, in other embodiments, as also shown in FIG. 8, the user or another person can add one or more cap modular pieces 710 a, 710 b, 710 c, 710 d in between each cap corner piece 708 a-708 d to achieve the desired sized modular return air plenum 700 as made up of the cap 702 and the base 704. Accordingly, the cap 702 when assembled is intended to be placed over the top surfaces of the assembled base 704 to form a single modular return air plenum 700. The cap 702 can be removably pressed onto the base 704 and in this way may be easy to attach the cap 702 to the base 704 as needed and easy to detach the cap 702 from the base 704 as needed.

It is noted that the HVAC technician can still stack multiple levels or layers of return air plenums 700 to achieve a final taller return air plenum 700 having the desired height to suit a particular air handler unit 104 or another HVAC unit.

FIG. 9 shows a partial view of a base corner piece 720 a connected to a base modular piece 722 a of the modular return air plenum 700. Each base corner piece 720 a-720 d can connect from each end to another base corner piece 720 a-720 d or to a base modular piece 722 a-722 d to create a joint 908, as shown in FIG. 9, between each connected or adjacent piece. The end pieces of each short side 705 of each base corner piece 720 a-720 d are designed to mate with the end pieces of each long side 707 of each L-shaped base corner piece 720 a-720 d so that a short side 705 of each corner piece 720 a-720 d can mate with the end piece of a long side 707 of each base corner piece 720 a-720 d. When the end pieces of the short sides 705 of the base corner pieces 720 a-720 d are pressed into the end pieces of the long sides 707 of the base corner pieces 720 a-720 d, as shown in FIG. 11, then a rectangle or square shaped base 704 of a modular return air plenum 700 is formed. Similarly, the end pieces of each short side of the cap corner pieces 708 a-708 d mate or fit into when pushed together the long pieces of each long side of the cap corner pieces 708 a-708 d. When all of the corner pieces 708 a-708 d of the cap 702 are assembled together, the cap 702 is formed. When all of the corner pieces 720 a-720 d are assembled together, the base 704 is formed.

If base modular pieces 722 needs to be added to each side (e.g. a front side 334, back side 336, left side 338, and right side 340 as shown in FIG. 8) of the cap 702 and of the base 704 in order for the cap 702 and the base 704 when pressed together to fit the area of the HVAC unit placed above the cap 702 and the base 704, then the user may add one or more base modular pieces 722 to the base 704 and one or more cap modular pieces 710 to the cap 702. The cap modular pieces 710 a-710 d connect in between the ends of each cap corner piece 708 a-708 d and the base modular pieces 722 a-722 d connect in between the ends of each base corner piece 720 a-720 d.

In a non-limiting embodiment, as shown in FIG. 9, at each end of the base corner pieces 720 a-720 d or modular pieces 722 a-722 d there may be a protruding bar piece 902 that is configured to fit in a receiving slot 908 (e.g., as also shown in FIG. 9) having the proper shape and size to fit the protruding bar 902. Accordingly, the end bar piece 902 on one base corner piece 720 mates with the receiving slot 908 on an adjacent base corner piece 720 a-720 b or an adjacent modular piece 722 a-722 d

The interior of each corner piece 720 a-720 d and modular piece 722 a-722 d may be hollow as shown in FIG. 9 and may include one or more channels 904 or bores that are separated by vertically aligned partitions 906. These channels 904 may help make the return air plenum 700 more light weight when assembled.

FIG. 10 shows a top perspective view of the top surfaces of the base corner pieces 720 a-720 d and modular pieces 722 a-722 d of the base 704 of the return air plenum 700 according to one or more non-limiting embodiments. The cap 702 is not positioned over the base 704 of the return air plenum 700 in FIG. 10.

FIG. 11 shows an example of a base 704 of a return air plenum 700 that does not include base modular pieces 722 a-722 d. Rather, as shown in FIG. 11, the base corner pieces 720 a-720 d are each connected to each other to form a square or rectangular shape with an interior cavity 706 defined by the walls of the base corner pieces 720 a-722 d. Accordingly, there may be instances where the base corner pieces 720 a-720 d can be connected to each other and define an interior cavity 706 to form a sufficient sized return air plenum 700 to support an HVAC unit without the use of base modular pieces 722 a-722 d.

As shown in FIG. 10 and in FIG. 11, the corner pieces 720 a-720 d may have a corner piece protruding piece or boss 1002 that runs along the top of each of the corner pieces 720 a-720 d in one or more non-limiting embodiments. Accordingly, a first portion 1004 of the corner piece boss 1002 may cover and extend above the top surface of the long side 707 and a second portion 1006 of the corner piece boss 1002 may cover and extend the top surface of the short side 705 of each base corner piece 720 a-720 d. Similarly, each modular piece 722 a-722 d may have a modular piece boss 1008, as shown in FIG. 10, that covers and extends above the top surface of each base modular piece 722 a-722 d. The boss pieces 1002 of the base corner pieces 720 a-720 d and the boss pieces 1008 of the base modular pieces 722 a-722 d are intended to press within the underside of the flat cap 702 pieces when the flat cap 702 as assembled is pushed onto the assembled pieces (e.g., base corner pieces 720 a-720 d and/or base modular pieces 722 a-722 d of the base 704). Accordingly, the boss pieces 1002 of the base corner pieces 720 a-720 d can be pressed into and fits within an underside of the cap corner pieces 708 a-708 d. Similarly, the boss pieces 1008 of the base modular pieces 722 a-722 d fit within an underside of the cap modular pieces 710 a-710 d (e.g., as shown in FIG. 8) so that the cap 702 can fit over the base 704. As shown in FIG. 7 and in FIG. 8, the cap 702 when positioned or pressed onto the connected top surfaces of the base 704 covers up the boss pieces 1002 of the base corner pieces 720 a-720 d and the boss pieces 1008 of any base modular pieces 722 a-722 d used to form the base 704 of the modular return air plenum 700.

The boss pieces 1002 of the base corner pieces 720 a-720 d and the boss piece 1008 of the base modular pieces 722 a-722 d may be designed to fit within a hollow underside of the cap corner pieces 708 a-708 d and the cap modular pieces 710 a-710 d. As shown in FIG. 8, the boss pieces 1002 of the base corner pieces 720 a-720 d and the boss piece 1008 of the base modular pieces 722 a-722 d are not visible when the cap 702 is covering the top surfaces of the base 704 of the modular return air plenum 700. Rather, the joinder line 802 is visible from each side 334, 336, 338, 340 of the formed modular return air plenum 700 where the cap 702 joins and is removably attached to the top surfaces of the base 704. In one or more non-limiting embodiments, the boss pieces 1002 and 1008 may provide a tighter friction fit and connection between the base 704 and the underside of the cap 702 when the boss pieces 1002 and 1008 are designed to fit inside the hollow undersides or openings of the cap 702.

As shown in FIG. 8, the length and width of the cap corner pieces 708 a-708 d are equivalent to the length and width of the base corner pieces 720 a-720 d. Similarly, the length and width of the cap modular pieces 710 a-710 d are equivalent to the length and width of the cap modular pieces 722 a-722 d. Notably, as shown in FIG. 8, a height of the cap corner pieces 708 a-708 d is shorter than the height of the cap base pieces 720 a-720 d. The cap 702, accordingly in one or more non-limiting embodiments, has a shorter height in comparison to the base 704 of the modular return air plenum 700.

As noted above, and as shown in FIGS. 7-8 and FIG. 11, the L-shaped base corner pieces 720 a-720 d are configured to tightly mate with one another or with intervening base modular pieces 722 a-722 d. As shown in FIG. 8, the base modular pieces 722 a-722 b may have a generally rectangular shape with the boss piece extended along the top of the base modular pieces 722 a-722 b. The protruding bar 902, as shown in FIG. 9, may extend down one lateral side of the base modular pieces 722 a-722 d and may include a receiving slot 904 on the opposite lateral side of the base modular pieces 722 a-722 d. As shown in FIG. 9, the protruding piece 902 that may extend down a lateral side of a base corner piece 720 a-720 d that is configured to mate with a receiving slot 904 of another base corner piece 720 a-720 d or a base modular piece 722 a-722 d. The receiving slot 904 of the base corner piece 720 a-720 d and of the base modular piece 722 a-722 d may be formed to generally match a cross-sectional shape of the protruding piece 902. The same is true for the cap corner pieces 708 a-708 d and the cap modular pieces 710 a-710 d whereby there are ends configured to mate with each adjacent cap corner piece 708 a-708 d and cap modular piece 710 a-710 d. The first mating end piece of each base corner pieces 720 a-720 d and each base modular pieces 722 a-722 d, as well as the first mating end piece of each cap corner piece 708 a-708 d and each cap modular piece 710 a-710 d may fit with another adjacent piece (whether the adjacent piece is a corner piece 720,708 or a modular piece 722,710) by interference fit. Interference fit may also be referred to as press fit or friction fit, in which two tight fitting mating parts are pressed together to produce a joint which is held together by friction after the parts are pushed together.

FIG. 12 is a flowchart of an exemplary method of assembly and/or use of the modular return air plenum 700. In a non-limiting embodiment, in order to use a modular return air plenum 700, as shown at step 1202, the user may measure the width and length of the HVAC unit (e.g., air handler unit 104 or furnace 202) in order to obtain the area needed for the HVAC unit. The user needs to know the width and length of the bottom of the HVAC unit in order for the user to know how big or small the final return air plenum 700 needs to be to support the bottom of the HVAC unit. As noted above, the final assembled return air plenum 700 (e.g., as made up by the cap 702 and the base 704) may be placed beneath the HVAC unit so that the HVAC unit is vertically aligned with the final assembled return air plenum 700. Alternatively, the HVAC unit may be turned on its side and the final assembled return air plenum 700 is connected or placed to the side of the connected flat cap 702 and base 704 of the return air plenum 700. In this arrangement, the HVAC unit is horizontally aligned with the assembled return air plenum 700 as made up by a completed, connected flat cap 702 and base 704.

Once the user knows the width and length of the final return air plenum 700, at step 1204, the user or another entity may determine the necessary number of base corner pieces 720 a-d for the base 704 in order to suite the area of the HVAC unit. Similarly, at step 1206, the user or another entity may determine the necessary number of base modular pieces 722 a-722 d for the base 704 in order to suit the area of the HVAC unit that will be supported by the combination of the cap 702 and base 704 (e.g., as shown in FIG. 7).

At step 1208, based on the determination made for the number of base corner pieces 720 a-720 d and the number of base modular pieces 722 a-722 d of the base 704 of the return air plenum 700, the user or another entity may assemble or gather the same number of cap corner pieces 708 a-708 d as the number of the base corner pieces 720 a-720 d. Further, the user may assemble or gather the same number of cap modular pieces 710 a-710 d as the number of base modular pieces 722 a-722 d and insert one or more cap modular pieces 710 in between each cap corner piece 708 as needed.

At step 1210, the method may include connecting the base corner pieces 720 a-720 d of the base 704 together and connecting any optionally used modular pieces 722 a-722 d to form the completed base 704 of the modular return air plenum 700. At step 1212, the method may further include connecting the corner pieces 708 a-708 d of the cap 702 and connecting any optionally used modular pieces 710 a-710 d to form the completed cap 702 of the modular return air plenum 700.

At step 1214, the method includes positioning the completed cap 702 over the top of the completed base 704 to form the fully assembled modular return air plenum 700. At this point, the user or other entity may position the modular return air plenum 700 beneath an HVAC unit (e.g., as shown in FIG. 7) or may position to the side of the HVAC unit if the HVAC system is designed in such a manner that the HVAC unit needs to be supported on its side by the assembled modular return air plenum 700 rather than being supported in a vertical arrangement (e.g., as shown in FIG. 7). The cap 702 and base 704 shown in FIGS. 7-11 are intended to be modular and adjustable to create a custom size and shaped modular return air plenum 700 to best suit the HVAC unit that the cap 702 and the base 704 of the modular return air plenum 700 are intended to support and be coupled to. The cap 702 and base 704 when coupled together may be oriented in any desired direction or orientation to best suit the HVAC unit and HVAC system.

Further, if additional height is needed, the user may stack multiple completed bases 704 and/or flat caps 702 on top of each other. When the desired number of bases 704 are stacked on top of each other, the user may apply or position the completed flat cap 702 over the last base 704 as stacked over another set of bases 704 and position the HVAC unit over or adjacent to the flat cap 702 and connected set of bases 704 if needed.

The base corner pieces 720 a-720 d of the base 704 and the corner pieces 708 a-708 d of the flat cap 702 are designed to be the same width and length as each other as shown in FIGS. 7-8. Accordingly, the flat cap corner pieces 708 a-708 d when coupled to the top surfaces of the base corner pieces 720 a-720 d of the base 704, do not extend over the corner pieces 720 a-720 d of the base 704. Further, the modular interior pieces 722 a-722 d of the base 704 and the modular pieces 710 a-710 d of the cap 702 have the same width and length also as shown in FIG. 7 and FIG. 8.

In one or more non-limiting embodiments, the cap 702 and base 704 may be made of plastic in one or more non-limiting embodiments to ensure that the cap 702 and base 704 are lightweight and easy to manufacture and store in abundant quantities. In other embodiments, the cap 702 and the base 704 of the return air plenum 700 may be made of foam to also be lightweight. Other types of materials may alternatively be used.

Advantageously, the return air plenum 700 shown in FIGS. 7-11 is designed to be modular and adjustable in its size. Accordingly, as many modular pieces 722 a-722 d can be added to any side, including the front side 334, back side 336, left side 338, and right side 340 of the return air plenum 700 as needed to achieve the proper height 312, width 314, and depth 316, as shown in FIG. 3, to best suit the HVAC unit (e.g., air handler unit 102 or furnace 202 shown in FIGS. 1-2) that the modular return air plenum 700 is intended to support. Accordingly, the modular pieces 722 a-722 d in one or more non-limiting embodiments, can be added in any number or arrangement in between the base corner pieces 720 a-720 d in the embodiment shown in FIGS. 7-11 in order to achieve the correct height 312, width 314, and length 316 for the return air plenum 700. It is noted if the corner pieces 720 a-720 d when joined together provide the proper 312, width 314, and depth 316, as shown in FIG. 3 to best suit the HVAC unit the overall modular return air plenum 700 is configured to support, then there is no need to add additional modular pieces 722 a-722 d on each side of the modular return air plenum 700. It is advantageous that by adding or removing modular pieces 722 a-722 d, the user can easily alter the size of the overall modular return air plenum 700.

Further, as noted above, the return air plenum 700 can be stacked on top of each other, similar to the example shown in FIG. 6, in order to have more than one level or layer in order to provide the correct and desired height 312 for the overall return air plenum 600.

In cases where the HVAC technician needs a taller return air plenum 700 to support a specific type of unit, the HVAC technician can stack any number of return air plenums 700 arranged as desired and also having the desired width 314 and length 316 on top of each other. Advantageously, because the base corner pieces 720 a-720 d, base modular pieces 722 a-722 d, cap corner pieces 708 a-708 d, and cap modular pieces 710 a-710 d are lightweight and modular, the user can easily transport these components as individual units to a work site and assemble the units onsite to suit or fit the HVAC unit as needed.

It is noted that return air plenums 300 or 700 can be arranged in horizontal configurations to support a nearby unit (e.g., an air handler unit 102 or furnace 202 as shown in FIGS. 1-2) and are not limited to a vertical arrangement or positioning. Accordingly, return air plenums 300 or 700 as shown in FIGS. 1-11 may not always be positioned beneath a unit but rather adjacent to the underside or bottom side of a unit but in a horizontal orientation or direction or any other orientation as needed.

Many other advantages and benefits may be provided by the one or more systems and components described herein.

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention.

In the Summary above and in this Detailed Description, and the claims below, and in the accompanying drawings, reference is made to particular features (including method steps) of the invention. It is to be understood that the disclosure of the invention in this specification includes all possible combinations of such particular features. For example, where a particular feature is disclosed in the context of a particular aspect or embodiment of the invention, or a particular claim, that feature can also be used, to the extent possible, in combination with and/or in the context of other particular aspects and embodiments of the invention, and in the invention generally.

The term “comprises” and grammatical equivalents thereof are used herein to mean that other components, ingredients, steps, among others, are optionally present. For example, an article “comprising” (or “which comprises”) components A, B, and C can consist of (i.e., contain only) components A, B, and C, or can contain not only components A, B, and C but also contain one or more other components.

Where reference is made herein to a method comprising two or more defined steps, the defined steps can be carried out in any order or simultaneously (except where the context excludes that possibility), and the method can include one or more other steps which are carried out before any of the defined steps, between two of the defined steps, or after all the defined steps (except where the context excludes that possibility).

The term “at least” followed by a number is used herein to denote the start of a range beginning with that number (which may be a range having an upper limit or no upper limit, depending on the variable being defined). For example, “at least 1” means 1 or more than 1. The term “at most” followed by a number is used herein to denote the end of a range ending with that number (which may be a range having 1 or 0 as its lower limit, or a range having no lower limit, depending upon the variable being defined). For example, “at most 4” means 4 or less than 4, and “at most 40%” means 40% or less than 40%. When, in this specification, a range is given as “(a first number) to (a second number)” or “(a first number)— (a second number),” this means a range whose lower limit is the first number and whose upper limit is the second number. For example, 25 to 100 mm means a range whose lower limit is 25 mm and upper limit is 100 mm.

Certain terminology and derivations thereof may be used in the following description for convenience in reference only and will not be limiting. For example, words such as “upward,” “downward,” “left,” and “right” would refer to directions in the drawings to which reference is made unless otherwise stated. Similarly, words such as “inward” and “outward” would refer to directions toward and away from, respectively, the geometric center of a device or area and designated parts thereof. References in the singular tense include the plural, and vice versa, unless otherwise noted. The term “coupled to” as used herein may refer to a direct or indirect connection. The term “set” as used herein may refer to one or more items.

The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. The present invention according to one or more embodiments described in the present description may be practiced with modification and alteration within the spirit and scope of the appended claims. Thus, the description is to be regarded as illustrative instead of restrictive of the present invention. 

What is claimed is:
 1. A system for a modular return air plenum for HVAC systems, comprising: a base, the base comprising: one or more base corner pieces, wherein the one or more base corner pieces are L-shaped, and include a first base corner piece that is generally perpendicularly oriented to a second base corner piece; and one or more base modular pieces wherein the one or more base modular pieces are configured to connect to another base corner piece or to a base modular piece, wherein each base corner piece of the one or more base corner pieces and each base modular piece of the one or more base modular pieces each have a first mating end and a second mating end, wherein the first mating end of each base corner piece is configured to mate with the second mating end of another base corner piece or with the second mating end of another base modular piece, wherein when the one or more base corner pieces are connected in a rectangular or square like arrangement with each other and/or with any base modular pieces, the base of the modular return air plenum is formed, wherein the formed base of the modular return air plenum comprises a base interior cavity; and a cap placed over a top surface of the base, the cap comprising: one or more cap corner pieces, wherein the one or more cap corner pieces are L-shaped, and include a first cap piece that is generally perpendicularly oriented to a second cap piece; and one or more cap modular pieces wherein the one or more cap modular pieces are configured to connect to another cap corner piece or to another cap modular piece, wherein each cap corner piece of the one or more cap corner pieces and each cap modular piece of the one or more cap modular pieces each have a first mating end and a second mating end, wherein the first mating end of each cap corner piece is configured to mate with the second mating end of another cap corner piece or with the second mating end of another cap modular piece, wherein when the one or more cap corner pieces are connected in a rectangular or square like arrangement with each other and/or with any cap modular pieces, the cap of the modular return air plenum is formed, wherein the formed cap of the modular return air plenum comprises a cap interior cavity; wherein the modular return air plenum comprises the formed cap removably attached to the top surface of the formed base, wherein a width and a length of the modular return air plenum is customizable to suit and support an HVAC unit.
 2. The system of claim 1, wherein each assembled modular return air plenum is stackable onto another assembled modular return air plenum when additional height is required to suit and support the HVAC unit.
 3. The system of claim 1, wherein the modular return air plenum is configured to support an air handler unit or a furnace in an HVAC system.
 4. The system of claim 1, wherein each top surface of each base corner piece comprises a boss or a protruding piece that is configured to fit within a hollow underside of the cap.
 5. The system of claim 1, wherein each base corner piece comprises a longer side that is perpendicular to a shorter side.
 6. The system of claim 5, wherein an end piece of the longer side comprises a protruding bar like member, wherein the end piece of the longer side is the first mating end.
 7. The system of claim 7, wherein an end piece of the shorter side comprises a slot configured to receive the protruding bar like member in order to mate with either a base modular piece of the one or more base modular pieces or to mate with another base corner piece, wherein the end piece of the shorter side is the second mating end.
 8. The system of claim 1, wherein an interior of each base corner piece is hollow with a number of vertically aligned partitions having spaces between each vertically aligned partition.
 9. The system of claim 1, wherein the second mating end is configured to tightly mate with the first second mating end by press fit or friction fit.
 10. A modular return air plenum, comprising: one or more base corner pieces, wherein the one or more base corner pieces are L-shaped, and include a first base corner piece that is generally perpendicularly oriented to a second base corner piece; and one or more base modular pieces wherein the one or more base modular pieces are configured to connect to another base corner piece or to a base modular piece of the one or more base modular pieces, wherein each base corner piece of the one or more base corner pieces and each base modular piece of the one or more base modular pieces each have a first mating end and a second mating end, wherein the first mating end of each base corner piece is configured to mate with the second mating end of another base corner piece or with the second mating end of another base modular piece, wherein when the one or more base corner pieces are connected in a rectangular or square like arrangement with each other and/or with any base modular pieces, the modular return air plenum is formed, wherein a width and length of the modular return air plenum is customizable to suit and support a size of an HVAC unit.
 11. The modular return air plenum of claim 10, wherein the modular return air plenum comprises an interior cavity.
 12. The modular return air plenum of claim 10, wherein multiple assembled modular return air plenums are stackable onto each other when additional height is required to suit and support the HVAC unit.
 13. The modular return air plenum of claim 10, wherein the modular return air plenum is configured to support an air handler unit.
 14. The modular return air plenum of claim 10, wherein the modular return air plenum is configured to support a furnace in an HVAC system.
 15. The modular return air plenum of claim 10, wherein each top surface of each base corner piece comprises a boss or a protruding piece.
 16. The modular return air plenum of claim 10, wherein each base corner piece comprises a longer side that is perpendicular to a shorter side.
 17. The modular return air plenum of claim 16, wherein an end piece of the longer side comprises a protruding bar like member, wherein the end piece of the longer side is the first mating end.
 18. The modular return air plenum of claim 17, wherein an end piece of the shorter side comprises a slot configured to receive the protruding bar like member in order to mate with either a base modular piece of the one or more base modular pieces or to mate with another base corner piece, wherein the end piece of the shorter side is the second mating end.
 19. The modular return air plenum of claim 10, wherein an interior of each base corner piece is hollow with a number of vertically aligned partitions having spaces between each vertically aligned partition.
 20. The modular return air plenum of claim 10, wherein the second mating end is configured to tightly mate with the first second mating end by press fit or friction fit. 